Broken windows are seen on the 32nd floor of the Mandalay Bay Resort and Casino after a gunman opened fire on the Route 91 Harvest country music festival on Sunday in Las Vegas. (David Becker/Getty Images)

Stein, who had served as Richard Nixon’s chief economic adviser, was referring to the trade deficit. But Stein’s Law has a wide application beyond economics — and it offers a dollop of comfort about gun violence after the Las Vegas massacre.

The political impasse over any form of gun regulation fits Stein’s definition of a trend that is unsustainable. A national poll in late June by Quinnipiac University found 94 percent of all voters favored background checks for all gun buyers and 57 percent believed it was currently too easy to purchase a gun.

On almost all gun questions in the Quinnipiac survey, younger voters were more willing than their older counterparts to support additional restrictions on gun purchases.

The symbiotic — and destructive — relationship between the National Rifle Association and congressional Republicans means the short-term legislative prognosis for any form of gun regulation is on the pessimistic side of nil. Gun safety crusaders will consider it a victory if they derail current NRA-backed bills to deregulate gun silencers and allow anyone with a concealed carry permit to use it in any state.

But, as we have learned in this century, social change can occur with blinding speed, especially with the support of younger voters. At the turn of this century, few would have dared predict that in 2017, gay marriage would be the law of the land and marijuana would be legal in states from California to Maine.

The $52 million that the NRA spent in the 2016 campaign — with a whopping $30 million supporting Donald Trump — may someday be regarded as a lucky bet by an imperiled advocacy organization. In its shrill extremism, the NRA increasingly resembles 1950s Southern segregationists waging a last-ditch battle against the forces of integration and tolerance.

According to a Pew Research Center national poll conducted this spring, a plurality of 44 percent of Americans believed the NRA had too much political influence. Tellingly, this view was shared by 29 percent of gun owners.

Living with the aftermath

The catalyst for eventual legislative action to regulate guns may be the social changes wrought by the almost daily mass murders bloodying the land. In the shocked horror after the Las Vegas shootings, there has been talk about limiting live concerts as too vulnerable to attack and installing metal detectors in the lobbies of all high-rise hotels.

Would loyalty to the NRA survive would-be concertgoers being reduced to watching their favorite performers on movie screens and TV sets? Are tired travelers likely to celebrate the Second Amendment as they wait in never-ending security lines to get to their hotel rooms and a restorative shower?

The argument that America will eventually find a way to reduce gun violence and the incidence of mass murder depends on an important factor outside the control of the NRA and their willing GOP congressional servants.

And that is: Have gun control crusaders learned from their failed efforts to legislate in the wake of school children dead in Sandy Hook, churchgoers murdered in Charleston and night-clubbers massacred in Orlando?

Getting past the rhetoric

Raw emotionalism — no matter how deeply felt — does not change votes in Congress. If Barack Obama’s tearful sermons could not alter the gun debate, then it is unlikely the next overwrought speech on the Senate floor will turn the tide.

What the NRA and right-wing politicians have exploited is the cultural divide between gun owners and advocates for reform. The Pew poll found that 57 percent of Republicans but only 25 percent of Democrats lived in households where there was a gun. Similarly, 46 percent of those in rural America but only 19 percent in urban areas had guns in their homes.

As a result, too many gun control efforts can be dismissed as liberal elites lecturing Middle America about the moral and macho failures of the gun culture. Obama himself reflected this disdainful worldview when he was taped during a 2008 fundraiser saying about small towns in Pennsylvania, “It’s not surprising … they cling to guns or religion or antipathy toward people who aren’t like them.”

Another mistake by crusaders against gun violence has been to overhype proposed remedies.

Most studies suggest the 1994 assault weapons ban (signed into law by Bill Clinton, but which expired after 10 years) failed to significantly reduce gun deaths. Other proposed reforms, such as more effectively regulating purchases at gun shows, also would only work at the margins of the gun problem.

The dilemma for moderate legislators from states with strong gun traditions is: Why cast a vote certain to enrage the NRA if the reforms are mostly cosmetic? Preventing presumed terrorists on the no-fly list from purchasing guns polls well, but it is totally peripheral to the real-world gun debate in America.

One of the smartest liberal responses in the wake of the Las Vegas massacre came from an organization called Sandy Hook Promise, which grew out of the 2012 school shooting. Frustrated with the ritualized gun debates, the group issued a statement urging, “Let’s move from rhetoric and focusing on just ‘the gun’ to more focus on ‘the shooter’ and steps we can be taking as a country to identify and stop them before it’s too late.”

Nothing in the Constitution prevents a massive investment in mental health in the immediate wake of Las Vegas. And the hope remains that “Second Amendment remedies” will someday come to refer to legislation designed to keep guns out of the hands of the violent and mentally unstable.

Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and The Washington Post. Follow him on Twitter @MrWalterShapiro.Get breaking news alerts and more from Roll Call on your iPhone or your Android.